1. Field of the Invention
The present invention relates to a mask employed in a step of fabricating a semiconductor device or the like.
2. Description of the Prior Art
In general, a mask is employed for imparting a constant pattern onto a substrate in a step of fabricating a semiconductor device or the like. In order to manufacture this mask, a mask preparation system executes a mask preparation job. FIG. 8 shows the contents of a general mask preparation job. The system accepts mask pattern information and carries out a rendering step S1 on the basis of this information. Then, the system carries out a development step S2, an etching step S3 and an inspection step S4. A mask passing the inspection step S4 is regarded as a completed mask.
Following recent refinement and densification of the structure of a semiconductor device, a mask required therefor is also improved in precision and refined. Further, fabrication of mask patterns is complicated due to techniques such as shrink shrinking and fitting a pattern in a constant section at a constant magnification, optical proximity correction (OPC) correcting the thickness or the like in consideration of the difference between quantities of actually arriving light and the like. While a single mask pattern may include a generic part and a specific part or a part requiring high precision and a part requiring moderate precision, the rendering step disadvantageously requires excess time if the mask pattern is collectively prepared by the conventional mask preparation job.
An object of the present invention is to provide a method of manufacturing a mask capable of efficiently manufacturing a mask having a desired mask pattern.
In order to attain the aforementioned object, the method of manufacturing a mask according to the present invention comprises a mask preparation step of dividing a first desired mask pattern into a first mask pattern part and a second mask pattern part and performing rendering, development and etching on the first and second mask pattern parts independently of each other for preparing a first mask having the aforementioned first mask pattern part and a second mask having the second mask pattern part independently of each other and a first superposition step of superposing the aforementioned first mask and the aforementioned second mask for combining the aforementioned first mask pattern part and the aforementioned second mask pattern part with each other so that the upper surfaces and the lower surfaces of the aforementioned first and second mask pattern parts are flush with each other respectively thereby forming the aforementioned first desired mask pattern. According to this method, a desired mask pattern can be obtained by separately preparing masks in a divided manner in response to the difference between conditions of mask pattern parts included in the desired mask pattern and thereafter combining these masks with each other, whereby useful processing can be properly performed in response to the mask pattern parts for enabling efficient work.
In order to attain the aforementioned object, a mask according to the present invention comprises a first mask having a first mask pattern and a second mask having a second mask pattern prepared independently of each other, while the aforementioned first mask and the aforementioned second mask are superposed for combining the aforementioned first mask pattern part and the aforementioned second mask pattern part with each other so that the upper surfaces and the lower surfaces of the aforementioned first and second mask pattern parts are flush with each other respectively. According to this structure, the mask can be obtained by separately preparing the first and second mask patterns and combining the same with each other, whereby the mask can be efficiently manufactured.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.